Hydroxy-terminated arylene ethers, and method for making

ABSTRACT

A method is provided for making certain hydroxy-terminated arylene ethers useful as spacers in liquid crystalline polyesters. There is initially formed a dicarbonyl adduct from a dihydroxyaromatic compound, such as hydroquinone and a haloarylcarbonyl compound. The adduct formed is oxidized to the corresponding diester. Hydrolysis of the diester provides the hydroxy-terminated arylene ether.

This application is a division, of application Ser. No. 07/371,853,filed 06/26/89, which is a division of application Ser. No. 07/226,594,filed 08/01/88 now U.S. Pat. No. 4,873,371.

BACKGROUND OF THE INVENTION

The present invention is directed to a method for making certainhydroxy-terminated arylene ethers, such as 4,4'[arylbis(oxy)]bisphenolsincluded within the formula,

    HO--R.sup.1 --O--R--O--R.sup.1 --OH,                       (1)

where R is a member selected from the class consisting of C.sub.(6-36)arylene groups and C.sub.(6-36) arylene groups substituted withmonovalent radicals inert during hydroxy-terminated arylene-formingreactions, R¹ is a member selected from the class consisting ofC.sub.(6-20) divalent arylene radicals and C.sub.(6-20) divalent aryleneradicals substituted with monovalent radicals inert duringhydroxy-terminated arylene ether-forming reactions. Thehydroxy-terminated arylene ethers of formula (1) are made from certaindihydroxyaromatic compounds defined below. The hydroxy-terminatedarylene ethers of formula (1) are useful as flexible spacers in liquidcrystalline aromatic polyesters.

Prior to the present invention, certain 4,4'[arylbis(oxy)]bisphenolsincluded within formula (1) were prepared by the copper catalyzedUllmann condensation of 4-methoxyphenol with a dihaloaromatic compoundfollowed by demethylation of the resulting bismethyl ether. A lesscommonly used procedure for the preparation of4,4'[arylbis(oxy)]bisphenols is the Ullmann condensation of1-bromo-4-methoxybenzene with a dihydroxyaromatic compound followed bydemethylation of the resulting bismethyl ether. The advantage of thesecond method is that readily available dihydroxyaromatic compounds canbe used as starting materials.

SUMMARY OF THE INVENTION

The present invention is based on the discovery that thehydroxy-terminated arylene ethers included within formula (1), can bemade by a three-step procedure involving

(1) treating a dihydroxyaromatic with a benzophenone or benzaldehydehaving a leaving group in the para position selected from the classconsisting of fluoro, bromo, and nitro in the presence of a phenoldeprotonating agent and a substantially inert organic solvent to formthe corresponding bis(arylene)ether,

(2) effecting a Baeyer-Villiger oxidation of the bis(arylene)ether ofstep (1) in the presence or absence of a catalytic amount of analkylsulfonic acid to provide the corresponding arylene etherdiester,and

(3) saponifying the arylene etherdiester of step (2) to form ahydroxy-terminated arylene ether included within formula (1).

STATEMENT OF THE INVENTION

There is provided by the present invention, a method for makinghydroxy-terminated arylene ethers of formula (1) comprising,

(1) effecting reaction between a dihydroxyaromatic compound and anarylcarbonyl compound having a leaving group in the para positionselected from fluoro, bromo, and nitro to form an arylene etherdicarbonyl adduct of the formula, ##STR1## (2) oxidizing the resultingarylene ether dicarbonyl adduct of step (1) to form the correspondingarylene ether diester, of the formula, ##STR2## (3 ) saponifying thearylene ether diester of step (2) to form the correspondinghydroxy-terminated arylene ether of formula (1),

where R, and R¹ are as previously defined, and X is a member selectedfrom the class consisting of hydrogen, a C.sub.(6-14) arylene group, andhalogenated derivatives thereof.

Radicals included by R of formulas (1)-(3) are, for example, phenylene,tolylene, biphenylene, chlorophenylene, naphthalene, etc., and radicalsincluded by the formula,

    --R.sup.2 --(Q).sub.a --R.sup.2 --,

where R² is a C.sub.(6-14) divalent aromatic radical selected fromhydrocarbon radicals and halogenated hydrocarbon radicals, and Q is adivalent organo radical selected from ##STR3## where a is 0 or 1, y isan integer having a value from 1-5 inclusive, and R³ is monovalenthydrocarbon radical selected from methyl or phenyl.

Radicals included in R¹ are, for example, ##STR4##

Inert radicals which can be chemically bound to R and R¹ are preferablyhalo, such as chloro, and C.sub.(1-8) alkyl such as methyl. Radicalsincluded within X of formula (3) are, for example, phenyl, tolyl, xylyl,and chlorophenyl.

Dihydroxy aromatic compounds, which can be used in the practice of thepresent invention to make the hydroxy-terminated arylene ethers offormula (1), are compounds included within the following formula,

    HOR--OH,                                                   (4)

where R has been previously defined. Some of these dihydroxyaromaticcompounds which can be used in the practice of the present inventionare, for example, hydroquinone, 4,4'-oxydiphenol, 4,4'-biphenol,6,6'-dihydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane,2,6-dihydroxynapthalene, and 4,4'-(1-methylethylidene)bisphenol.

Phenol deprotonating agents which can be used in the practice of thepresent invention are, for example, alkali or alkaline earth metalcarbonates, or hydroxides, such as potassium carbonate, sodium orpotassium hydroxides, magnesium carbonate, etc. Choice of a particulardeprotonating agent will be influenced by the organic solvent used andits solubility therein.

Oxidizing agents which can be used to convert the arylene etherdicarbonyl adduct of formula (2) to the corresponding diester are, forexample, peroxides such as 3-chloroperoxybenzoic acid, hydrogenperoxide, performic acid, peracetic acid, etc.

Substantially inert organic solvents which can be used are, for example,dipolar aprotic solvents such as dimethyl acetamide,N-methylpyrollidinone, dimethylformamide, and dimethylsulfoxide.

In the practice of the preferred form of the present invention, reactionis effected between the dihydroxyaromatic compound of formula (4) and afluoroarylaldehyde, such as 4-fluorobenzaldehyde in the presence of ananhydrous alkali metal carbonate, such as potassium carbonate, and adipolar aprotic solvent, such as dimethylacetamide.

Alternatively, there can be used a fluoroarylketone, such as4-fluorobenzophenone if desired. There is produced an arylene etherdicarbonyl adduct of formula (2), such as the correspondingbis(4-formylphenyl)ether, where X is hydrogen orbis(4-benzoylphenyl)ether where X is phenyl.

Oxidation of the arylene ether dicarbonyl adduct of formula (2) can beachieved with 3-chloroperoxybenzoic acid in the presence or absence of acatalytic amount of an alkanesulfonic acid, such as methanesulfonic acidto produce the corresponding arylene ether diester, such as thebis(4-formyloxyphenyl)ether derivative or bis(4-benzoyloxyphenyl)etherderivative.

The hydroxy-terminated arylene ether of formula (1) can be made bysaponifying the resulting arylene ether diester of formula (3) with analkali metal hydroxide solution, such as a methanolic KOH solution.

The hydroxy-terminated arylene ethers of the present invention can beused as flexible spacers in the production of aromatic polyestersexhibiting anisotropic properties in the molten state.

The following examples are given by way of illustration and not by wayof limitation. All parts are by weight.

EXAMPLE 1

There was added 41.5 grams (0.30 mole) of anhydrous potassium carbonateto a solution of 11 grams (0.10 mole) of hydroquinone, 24.8 grams (0.20mole) of 4-fluorobenzaldehyde and 200 ml of dimethylacetamide. Theresulting solution was heated at reflux for 12 hours. The reactionmixture was then decanted from the insoluble potassium salts and allowedto cool. The cooled solution was added to water to effect precipitationof product which was isolated by filtration. The product wasrecrystallized from isopropanol/water to yield 21 grams (66%) of4,4'[1,4-phenylenebis(oxy)]bisbenzaldehyde having a melting point of157°-158° C. The identity of the product was further confirmed by protonNMR.

A solution of 15.92 grams (0.05 mole) of the above bisbenzaldehyde and150 ml of chloroform was treated while it was stirred with 21.57 grams(0.125 mole) of 3-chloroperoxybenzoic acid over a period of 10 minutes.After one hour, the solvent was evaporated and the resulting solidsslurried with 150 ml of cold methanol. The solution was filtered and thefilter cake washed with methanol. The isolated solid was dried in vacuoto provide 14.4 grams (82%) of 4,4'[1,4-phenylenebis(oxy)]bisphenoldiformate. Structure was confirmed by proton NMR.

A solution of 60 grams (0.65 mole) of potassium hydroxide in 100 ml ofmethanol was added with stirring at room temperature to a solution of10.5 grams (0.03 mole) of the above bisphenoldiformate and 50 ml ofmethanol. The resulting mixture was stirred for one hour at roomtemperature. The methanol was then evaporated and the resulting soliddissolved in a minimal amount of water. Upon acidification, a solidprecipitated from the solution. The resulting precipitate was filteredand there was obtained 8.21 grams (0.028 mole), or 93% of product. Basedon ¹ H-NMR, method of preparation, the product was4,4'-[1,4-phenylenebis(oxy)]bisphenol of the formula, ##STR5##

The above procedure was repeated except that in place of hydroquinonewhich provided "a" in Table I below, there was used several additionaldihydroxyaromatic compounds included within formula (4), where R is amember selected from ##STR6## which corresponds to the otherhydroxy-terminated arylene ethers of Table I. The following results wereobtained, where "Compounds" means hydroxy-terminated arylene ethers:

                                      TABLE I                                     __________________________________________________________________________          Recrystallization                                                       Compounds                                                                           Solvent  mp °C.*                                                                      .sup.1 H-NMR (DMSO/TMS, 90 MHz), δ                 __________________________________________________________________________    a     Toluene  188-189                                                                             6.67-7.00 (m, 12H), 9.30 (broad s, 2H)                   b     Toluene  195-197                                                                             6.70-7.20 (m, 16H), 9.37 (broad s, 2H)                   c     Toluene  205.5-210                                                                           1.30 (s, 12H), 2.26 (q, 4H), 6.27 (d,                                         2H), 6.65-6.91 (m, 12H), 7.20 (d, 2H), 9.3                                    (broad s, 2H)                                            d     Toluene  170-172                                                                             6.23 (broad s, 2H), 6.78-7.10 (m, 4H),                                        7.13-7.40 (m, 4H), 7.70-7.90 (d, 2H)                     e     Toluene  231-234                                                                             6.73-7.13 (m, 12H), 7.60 (d, 4H) 9.43                                         (broad s, 2H)                                            __________________________________________________________________________     *Melting points are uncorrected.                                         

EXAMPLE 2

A mixture of 40.01 grams (0.2 mole) of 4-fluorobenzophenone, 11.01 grams(0.1 mole) of hydroquinone, and 500 ml of dimethylsulfoxide was stirreduntil the solids had dissolved. There was then added 41.46 grams (0.3mole) of anhydrous potassium carbonate. The solution was then heated at135°-155° C. for 50 hours. The mixture was then treated with 200 ml ofcold water. A solid precipitated which was filtered and recrystallizedfrom orthodichlorobenzene. There was obtained 38.8 grams (0.87 mole) oran 87% yield of product. Based on ¹ H-NMR and the method of preparation,the product was 4,4'[1,4-phenylenebis(oxy)]bisbenzophenone.

A mixture of 22.3 grams (0.05 mole) of the above arylene etherbisbenzophenone, 25.8 grams (0.15 mole) of 3-chloroperoxybenzoic acid,400 ml of chloroform, and 1 ml of methanesulfonic acid was stirred atroom temperature for 70 hours. The solid was then evaporated and theresulting solid was slurried in 150 ml of methanol. The solution wasfiltered and the filter cake washed with methanol. The isolated solidwas dried overnight in a vacuum oven to provide 25.1 grams of crudeproduct. The isolated product was recrystallized from a minimal amountof dimethylsulfoxide to yield 17.8 grams (0.043 mole) or 86% yield ofthe product. Based on ¹ H-NMR and the method of preparation, the productwas 4,4'[1,4-phenylenebis(oxy)]bisphenol dibenzoate.

A solution of 2.46 grams (0.044 mole) of potassium hydroxide and 100 mlof methanol was added to a solution of 4.78 grams (0.01 mole) of theabove dibenzoate in 50 ml of methanol. The resulting solution wasrefluxed for three hours. The solvent was then evaporated and theresulting solid dissolved in 100 ml of water and acidified to pH˜1 withconcentrated HCl. The resulting precipitate was isolated by filtration,and dried overnight in a vacuum oven. The crude product wasrecrystallized from toluene to provide 2.9 grams (9.86 millimole) or98.6% yield of product. Based on the characterization data in Table IIbelow and the method of preparation, the product was4,4'[1,4-phenylenebis(oxy)]bisphenol.

Following the same procedure, dihydroxy-aromatic compounds within thescope of formula (4) were converted to hydroxy-terminated aryleneethers. Some of the dihydroxyaromatic compounds were the samedihydroxyaromatic compounds used to make compounds "a-c", shown forExample 1. Additional dihydroxyaromatic compounds were also used, whereR is f and g, within the scope of formula (4), as follows: ##STR7## Thefollowing results were obtained, where compounds a, b, and c are thesame as shown in Table I, and "IPA" is isopropanol:

                  TABLE II                                                        ______________________________________                                                Recryst.           .sup.1 H-NMR (D.sub.6 -DMSO/TMS,                   Compounds                                                                             Solvent   mp, °C.*                                                                        90 Hz), δ                                    ______________________________________                                        a       Toluene   181-182  6.80 (broad s, 8H), 6.89                                                      (s, 4H), 9.25 (s, 2H)                              b       IPA/H.sub.2 O                                                                           196-198  6.63-7.10 (m, 16H), 9.20                           c       Toluene   189-191  1.13-1.47 (s, 12H), 2.23 (dd, 4H),                                            (s, 2H) 6.23 (d, 2H),                                                         6.47 (broad s, 12H)                                                           6.97-7.29 (m, 4H), 9.20 (s, 2H)                    f       --        oil      1.70 (s, 6H), 6.63-6.89                                                       (m, 12H), 7.12 (d, 4H)                             g       Toluene   172-174  6.69-7.22 (m, 12H), 7.90 d,                                                   4H) 9.75 (broad s, 2H)                             ______________________________________                                         *Uncorrected                                                             

Certain of the above hydroxy-terminated arylene ethers were respectivelyconverted to the corresponding diacetates and then separatelyintercondensed with acetoxybenzoic acid, hydroquinonebisacetate, andterephthalic acid to form polyesters. The respective polyesters werefound to display anisotropic properties when examined with a hot-stagepolarized light microscope.

Although the above examples are directed to only a few of the very manyhydroxy-terminated arylene ethers of the present invention, it should beunderstood that the present invention is directed to a much broadervariety of hydroxy-terminated arylene ethers as shown in the descriptionpreceding these examples.

What is claimed and sought to be protected by Letters Patent of theUnited States is as follows:
 1. The compound,4,4'[6,6'(3,3,3',3'-tetramethyl-1,1'-spirobiindanyl)bis(oxy)]bisphenol.